PLC how to program??


Thread Starter


i'd like to learn appliation of a PLC in a level control systems. i never experience a level systems using a PLC yet.
There are a lot of programming options for PLCs these days. Learning the software is not that difficult for anyone who understands relay logic. Some companies such as Horner Electric ("": ) even offer their software for free (Cscape v5.01), just download it from their web site.

More complex software is also available for those who want to program in SFC, State Logic, C++, and Function Diagram.

Robert Willis

You can download demo versions of Schneider Electric's software packages from

Concept Version 2.5 (IEC-61131-3 -- Modicon PLC)
ProWorxNxT Version 2.2 (Modicon 984LL)
PL7 PRO (Telemecanique)

Robert Willis
Square D Company
Houston, Texas

Daniel Chartier

For a look at basics of PLC programming, you could look at the following
siemens site (free tutorial):

Level detection can be digital (ON/OFF signal) if you choose something like a float switch; or it can be an analog (time varying) signal from many different types of level transmitters. You need to read the correct type of signal in an adequate range for your chosen PLC, and program a valid response from your system (open/close valves, start/stop pumps...). But you must start by
understanding the process and the controler.

Hope this helps,
Daniel Chartier